Knowing the weight of an aircraft at the time of take-off is a critical factor in terms of the safety, fuel usage and engine life and maintenance requirements. By way of example on a passenger aircraft the Flight Management System (FMS) is employed to calculate the total weight of the aircraft. The current procedure employed by the FMS is based on data extracted from the aircraft load sheet, for example the:                a) Aircraft Prepared for Service (APS) weight;        b) Cargo and passenger's hold baggage weight, based on adding the weight of individual items loaded onto the aircraft;        c) Weight of catering supplies loaded for the flight;        d) Fuel load; and        e) Total weight of passengers and their hand baggage.        
Based on the total weight calculated by the FMS the aircraft pilot has to make a decision as to the appropriate thrust settings to be employed in order to allow the aircraft to get off the runway and climb to the desired altitude. Other factors that may be taken into consideration for take-off by the pilot, in conjunction with the FMS, are the weather conditions, the runway length, and the altitude of the airport.
As will be appreciated by those skilled in the art, the engine thrust settings at take-off determine the amount of fuel used and significantly affects the interval between maintaining and servicing of the engines.
The weights describe at a) to d) above can be accurately determined. However, the “total weight of passengers and their hand baggage” is presently calculated by employing standard passenger weights for adults and children. This weight includes an allowance for hand baggage and is approved by the state of registration's regulatory authorities. For an adult this weight is usually taken to be 84 kg. In practice their can be a significant variance in the weight of passengers themselves and the hand baggage they bring onto the plane e.g. tall adult man who has hand baggage plus duty free will weigh significantly more than a small women with no hand luggage. This variance can become quite significant to the overall weight of a passenger aircraft which are routinely employed to transport several hundred passengers at a time.
As a result of the uncertainty in the data about the weight of the aircraft, and possible errors in that information, the current practice during take-off is to over compensate for the “total weight of passengers and their hand baggage” and thus use more thrust, and hence fuel, than is required. As will be appreciated by the skilled reader this over compensation is primarily for reasons of safety.
It is therefore an object of an embodiment of the present invention to obviate or at least mitigate the foregoing disadvantages of the methods of determining the weight of a body, and in particular an aircraft, as known in the art.
It is a further object of an embodiment of the present invention to provide a method and apparatus for accurately determining the weight of a body, and in particular a rolling body or vehicle e.g. an aircraft.
It is a further object of an embodiment of the present invention to provide a surface angle measuring device that may be employed within a method for accurately determining the weight of a body, and in particular a rolling body or vehicle e.g. an aircraft.